Visit any church and ask some of the congregation why they believe in God. If you do, you’ll probably hear a surprisingly narrow range of answers, which mainly concern having a personal relationship with God or enjoying a feeling of spiritual fulfillment. These reasons would have some way to go before they amounted to reasonable arguments in favour of the existence of God. But when believers rely upon objective cold facts to justify their belief, the God Debate is truly on.

There are several issues well-informed believers raise when seeking to prove that God exists. For instance, even those who believe in evolution will say that there must have been a god who created life in the first place.

Some physicists would respond by referring to a meteorite which crashed down in Australia in 1969 and which contained parts of RNA (which organisms use to replicate DNA). And so perhaps the earliest cells appeared on Earth after extraterrestrial organic materials landed here on a meteorite. This remains a minority (but important) scientific theory, partly due to the difficulties in reproducing RNA in a thermodynamically flat environment and in the absence of any cell membranes.

Nowadays the leading scientific theory is that the earliest organic molecules appeared in underwater stalagmite-type structures which were created by hydrothermal vents caused by the earth’s colliding tectonic plates. This is a new theory and some of the supporting research dates from as recently as 2005 and 2007. And so it’s too early to know whether this theory will join the various ideas about the origin of life which the scientific community has already discarded.

Other believers point to the creation of the universe. One of the key scientific developments of the twentieth century was the scientific community’s acceptance of the Big Bang. The Christian stance is simple: God caused it. After all, the Big Bang couldn’t have started out of nothing.

The scientific community has struggled to resolve this issue but it seems to be getting close. Last year Stephen Hawking predicted that M-theory will soon be perfected. When this happens, it will show that God wasn’t needed to kick-start the Big Bang. But if M-theory isn’t completed, science may have to start all over again. And what’s more, a significant minority of cosmologists doesn’t accept that there even was a Big Bang. If they are proved right, the effect on the God Debate will no doubt then depend on whatever theory comes along next.

Some believers argue that if the laws of physics were even slightly different to how they are, life as we know it would have been impossible. This is known as the Anthropic Principle. For instance, if the Weak Nuclear Force were a little weaker, all the hydrogen in the early universe would have turned to helium and so no stars would have formed; yet if it were stronger, the supernovas would have failed to discharge the planets containing heavy elements which are necessary to foster life. Since it is highly improbable that such fine-tuning of the laws of physics arose by chance, God must be responsible.

Sceptics respond by referring again to M-theory which is based on the premise that this is not the only universe in existence. Rather the number of universes is in the region of 10 followed by 500 zeros. And so it’s hardly a surprise that we find ourselves living in a universe whose laws of physics allow us to exist. Admittedly much of cosmology is counter-intuitive. Even so, many atheists probably wish that their response wasn’t quite so head-scratching.

And what about consciousness? If we were all created by a guided but random process of evolution, why is it that only humans have a consciousness? Science doesn’t yet know the answer. Believers say that the best explanation is that God gave us conscious thought. That’s because we are his special creation and we are to have dominion over the animal kingdom.

I will mention just one more matter. Some believers argue that the creation of the universe and the creation of life on the planet violates the Second Law of Thermodynamics. Therefore you need to posit a God who could create all of this and suspend the operation of the Law as he did so.

By now, you may have noticed a theme. Non-believers are faced with several questions along the following lines: if there isn’t a god, how do you explain [insert complicated event or phenomenon]? Atheists respond by admitting that they don’t know the answer yet but that there are some plausible explanations.

The believer on the other hand claims that he has the answer: it must have been God who did it. This stance is referred to as the God of the Gaps because it involves finding any gap in scientific knowledge and positing God as the default explanation. “Science can’t explain how the universe started? It must have been God.” “You want to know why we have a consciousness? God must have made us that way.”

No wonder atheists struggle to stifle a laugh. Science has frequently shown that phenomena previously attributed to God had a natural explanation all along. The atheist philosopher Daniel Dennett had in mind possibly the best example of this when he wrote, “The theory of evolution diminishes the best reason anyone has ever suggested for believing in a divine creator.”

But if God exists, it’s difficult to imagine any convincing positive evidence there could ever be which could prove it. Even strong proof would probably be disregarded by many people who would find it insufficient when weighed against all the reasons to doubt his existence. And so, if there is a god, maybe the only way in which his existence can be proved is by those with specialist knowledge applying a God of the Gaps reasoning. However this should only be done with caution and in the rare cases in which there is no feasible chance that a naturalistic answer to a particular question will ever be found. Nowadays the atheist movement may be loosely described as New Atheism. But don’t mistake New for Transient. This is a debate which will go on and on.